Test tone 440 impossible?

Question

Can anyone get Test Oscillator to produce a 440Hz tone? Try to adjust: it seems to snap to 439,90 or 440,20. Type it in and it snaps somewhere else as well.
Any smart tricks available? Though I admit, this is the real nitty-gritty of a professional audio application, concert pitch...
Thanks

Answer 1

In order to produce single cycle loop of a waveform within a sampler/rompler (a common technique for static synth waveforms which take up little memory), the frequency of the pitch in question has to divide evenly into the playback rate (44.1, 48, or whatever). Very few musical pitches actually divide evenly in this way.
So to circumvent this problem with single cycle looped waveforms, many samplers/romplers have a loop pitch offset parameter that can be adjusted to get the loop in tune. It's a combination of the playback engine's resolution, the root pitch itself, and the skill of the programmer which detemine whether the pitch of the single cycle loop is successfully brought into tune.
One way to avoid this pitfall is not to use single cycle loops. Instead, you attempt to loop multiple cycles of the waveform, the theory being that as you increase the loop length you'll reach a point (hopefully) where X number of cycles of the waveform (X times the frequency of the note) will divide evenly into the sample playback rate and allow for a perfectly in tune loop. While in some cases this can be achieved, there's no guarantee that your extended loop length, while now in tune, will fall on a zero crossing point of the waveform. This will produce clicks or pops. That's where crossfade looping techniques come in...
If anyone's interested in more of this gobble-t-gook I'd be happy to elaborate more.